Variable contour cam



1950 J. H. STALEY 2,517,142

VARIABLE CONTOUR CAM Filed April 22, 1948 vlll ll INvEIvToR, JOSEPH H. .S'TALE;

EMMA/J4 @TORNEY.

Patented Aug. 1, 1950 UNITED STATES PATENT GFFICE VARIABLE CONTOUR CAM Joseph H. Staley, Columbus, Ind. Application April 22, 1948, SerialNo, 22,592 3 Claims. witn ss?) This invention relates to a cam having an automatically variable contour which may be shortened and lengthened in regard to the direction of rotation of the cam. A primary purpose of the invention is to provide a cam structure whereby a cam follower may be quickly elevated relatively from a lower surface to a higher surface with what may be termed a snap action. A further primary advantage of the invention is that the cam will give a longer surface on which the follower may dwell in one direction of rotation of the cam as compared to an opposite direction of rotation of the cam.

The invention is particularly useful in electrically timing the stopping and starting and also sequence of operations inmany fields.

These and many other objects and advantages of the invention will become apparent to those versed in the art in the following description of one particular form of the invention as illustrated in the accompanying drawing, in which Fig. 1 is a view in side elevation of a cam structure embodying the invention and mounted on a shaft;

Fig. 2, a view in front elevation;

Fig. 3, a view in side elevation opposite to that 10Wll in Fig. 1; i

Fig. l, a view in section on the line l-l of Fig.

Fig. 5, a view in section on the line E-5 in Fig. 1; and 1 Fig. 6, a side elevation of a fragment of a modified form of the structure.

Referring to the drawing, in which like characters of reference indicate like parts throughout the several views, I provide a driving shaft Hi, on which is mounted a sleeve l l in a fixed manner such as by a set screw i2, Fig. 5, which screw passes through a head it on the sleeve. and bears against the shaft 99., On the sleeve H is placed a s ort bushing i l to bear against the inside face of the head 53.

A cam member l5 is provided with a central bore to permit the cam l5 to be inserted over the sleeve Hand have a running fit around the outside of the bushing M. A second cam member i6 is fitted over the sleeve H to have its central portion bear against the bushing Hi to retain it against the head i3. This cam member H5 is held in position in a fixed manner relative to the sleeve H by any suitable means, herein shown as by a pin ll inserted through the cam it, the bushing l4, and terminating within the head !3, Fig. 5.

A bushing l 3 is fitted over the sleeve l i to bear against the face of the cam it: and to receive therearound a third cam member 45. The cam member 55 may freely rotate around the bushing li. A nut 28 screw-threadedly engages the outer end of the sleeve H and is drawn therealong to compress the bushing ill against the cam member it and in turn compress the bushing id against the head it. Thus it is to be: seen that the cam members 5 555 are shift-able while .79 central m cber ifiis fixed al on to the sleeve ii, and consequ t e shaft Each of cam .memb a, '5, and i a circumferential edge portion Til, and as re spectively, Figs. 4 and 5, having a common radius of curvature from the center of t e shaft ill. This portion of each of the cam members having this common radius may extend the desired circumferential distance therearound depending upon the operations required, herein shown as approximately 180 degrees. This dimens on of course may vary, and also the contour of this length may also vary, although it is shown here in for the sake of illustration as having a corn stant radius. Then these same cam members l6, and it have another circumferential length 2-4, 25, and 26 respectively, of a common rad'us from the center of shaft Hi, this radius being less than the radius of the other portions just described of each of the cam members.

The cam member ilihas a post 27 fixed thereto to extend laterally therefromcthrough a win-- dow 23 provided in the cam member l5. Thus the cam member It may revolve around the bushing' M a limited distance as is determined by the post2'l striking opposite sides of the window 28. In order to maintain the cam member in an initial position relative to the central cam meiner l6, there is a spring 29 secured to the outer end of the post 2'! and extending along the outer face of the cam member l5 to have the other end of thespring 29 secured to a lug 38 that is at tached to the outer face of he cam member The spring 253 is stretched slightly Wren the post 2"! is in the pos-tion as indicated in Fig. 3. In other words, normally the cam member i5 is relatively pulled by the spring Zil around until the edge position of the window 28 strikes against the post 21.

Now in the same manner, there is a post 3i anchored in the central cam member iii to tend laterally therefrom, in a direction opposite fromthat of the post H. In other words the post 3! extends from the opposite face of the cam number Hi. In so doing, it extends through a window 32 which is provided in the cam member l9. Atension spring 53 is secured to the outer end of the post 3| and extends along the outer side face of the cam member l9 to have the other end of the spring 33 secured to a lug 34 attached to the outer face of the cam member l5, Fig. 1. In this manner, the cam member I9 is relatively rotated or revolved around the bushing 18 to have the edge portion of the window 32 strike against the post 3 l.

While the cam construction so far described may be employed to operate different mechais herein illustrated in con unction with a cam follower in a nature of a roller which is us d to operate a mercury tube switch 35. In the form herein shown, and not forming part of the invention per se, the cam follower roller 35 is carried by an arm 3'! which in turn is pivoted on the pins 38 ca ried by a bracket 39, in turn fixed to a panel Ml. The arm 3'! which in t e present showing is bifurcated extends upwardly from the pivot pins 38 to carry thereon a switch base ll in turn carrying the two clips 42 and 53 between wh ch the mercury tube switch 35 is rem ovably engaged.

Attention is to be focused upon the peripheral portions of the three cam members [5, I 6, and I9 which lie bet een the two circumferential ma or surfaces of the smaller and larger radii.

The contour of the cam member iii has a radial portion 44 which extends from a fillet 45 radially from the edge port on 25 outwardly and around through a, portion of a short radius i i to ,ioin into the edge portion 23. The contour of the cam member l has a short length of a substantially radial portion l'i extending upwardly from a radius at its juncture with edge port on 24 outwardly to a distance slightly greater at least than the radius of the roller 35. In other words this length 41 terminates at a transverse line 48, and from that point 58. the surface of the cam i5 slopes in a substantially straight line to the right, Fig. l, at an angle to the line l! of approximately 45 degrees to term nate in the outer or major edge portion 2i. The sloping part of the cam is designated by the numeral 49. Then the central cam member I5, is provided with an outwardly extending portion 59 inclined somewhat from the radial line, the l ne 5!! leaning somewhat to the right as viewed in Fig. 1 from the surface 25 to the outer surface 22.

Now these various intervening cam surface portions between the relatively lower and higher surfaces of the cam as assembled will normally be pos tion d as indic ted by the lines in Fig. 1. Assuming that the entire cam assembly is to be revolved in a counterclockwise direction as vie ed in Fig. 1. the portion 44 will be foremost in that line of directon of travel. Then spaced around in a clockwise direction will come the portion 4 and then spaced on further around in a clockw se direction is the portion 553. These are the pos tions of the sections l5 and i9 relative to it which are yieldingly maintained by the spr ngs 25 and 53 in the manner above described.

Now assum ng further that the cam assembly is to be revolved initially in a counterclockwise direction, and that the cam follower is resting upon the lower surfaces 24, 25, and 2'5, then the portion 44 of the cam ill will strike the roller 35. The cam member ill by reason of its radial line M will be stopped, and held against the roller 35 while the cam member l5 will bring its portion l! around against the roller 35 and since that portion is also substantially radial, it will also eifectively stop rotation of the cam member l5. In the meantime the cam member [6, the central member, will come on around until it strikes the roller 35. By reason of its inclined surface 50, the roller 35 will tend to be lifted to travel upwardly therealong.

However as soon as the roller 35 is lifted by the surface 5!] that distance which will permit the roller 35 to come up to the point 58, and tend to roll on the surface 39, the spring 23 will snap the cam member i5 on around counterclockwise so as to quickly elevate the roller 55 up to the common surfaces 21%, 22 and 23. Immediately the roller 35 reaches that elevation, t en the cam members l9 and 15, will be returned to their initial and normal positions as indicated in Fig. l, whereupon they effectively extend the length of those surfaces 2|, 22, and 23 when the cam assembly is reversely revolved, such as in a clockwise direction, in reference to the intersection of the line 50 and the surface 25. In other words, when the cam assembly is revolved clockwise, the roller 35 is held in the elevated position until it drops down over the radius 46 and down the radial surface M onto the surface 25.

One of the important advantages in this construction, particularly where the cam is used to operate a switch such as a mercury switch 38, in the absence of the cam member i5, the roller 35 would tend to travel relatively slowly up the surface 55, and before the roller 35 reached the maximum elevation of the surface the switch 36 would be operated, and if that switch 36 happened to be controlling the drive of the shaft 50, then of course the entire assembly would come to rest without any further travel of the shaft 18.

Referring to the modified form of the structure shown in Fig. 6, cam I5 is employed as the fixed, driven member as in the other forms. However, a shiftable cam member 55 is employed to be normally positioned by the spring 55 against the post 51 which is fixed to the member l6 and which extends through the window 58 in the member 55.

This member 55 has a notch 59 entering from its periphery 68 which is of the same radius of curvature as that of the cam member iii surface 22. A plunger type follower pin 5i rides on the combined surfaces 22 and 58. Assuming a clockwise direction of cam travel, the pin 5! will drop into the notch 59 to produce the required travel thereof effective for the control desired, such as the operation of a switch or any mechanical device, not shown, but within the knowledge of those versed in the art.

Upon dropping into the notch 59, the cam member 55 will then be yieldingly carried along until the cam I5 stops traveling, and then upon withdrawal of the pin iil (such as by a solenoid magnet, not shown), the cam member 55 will be snapped back by the spring 56, thereby presenting the surface 58 as a continuation of the combined surfaces 22 and 58, and against which surface 60 the pin 5| may return. The important feature in this modified form is, the automatical- 1y returning cam member to its normal position after having been yieldingly shifted therefrom, and to present a continuation of the outer cam surface under the follower.

While I have herein shown and described my invention in the two particular forms, it is obvious that structural changes may be employed without departing from the spirit of the invention, and I therefore do not desire to be limited to those precise forms beyond the limitations which may be imposed by the following claims.

I claim:

1. A cam structure having a cam follower comprising a relatively fixed cam member having a contour with relatively high and low surfaces a second cam member having a high surface laterally complementing in part at least said fixed cam high surface, and having a lower surface, all in the path of said follower; means yieldingly retaining said second cam in a predetermined position relative to said fixed cam member; said second cam member having a follower abutment between its said two surfaces; said position being that wherein said abutment is spaced from the zone between the two said surfaces of said fixed cam member in the direction of said fixed cam low surface extending therefrom; and a third cam member yieldingly retained in a predetermined position relative to both of said fixed and second cams; said third cam having a follower abutment in said predetermined position located between said zone and said second cam abutment; said third cam positioning means comprising a spring interconnecting it with said fixed cam, whereby said follower upon striking said second and third cam abutment may carry those abutments relatively into said fixed cam zone upon one direction of relative travel of said fixed cam zone and said follower toward each other; said zone having an inclined surface from the fixed cam low to high surfaces shaped to lift said follower thereover; and said third cam havinga peripheral slope from its abutment to its high surface permitting said third cam spring to snap said third cam back under said follower in said travel.

2. A cam and cam follower structure comprising a driving member; a drive cam fixed to said member, said cam having a major radius surface and a minor radius surface and a non-radial surface therebetween sloping rearwardly in respect to direction of rotation of the cam; a second cam revolubly carried by said member adjacent said drive cam, having a major radius surface and a minor radius surface and a substantially radially disposed surface therebetween; spring means normally advancing in direction of the drive cam rotation said radially disposed surface ahead of said drive cam non-radial surface; abutment means between the drive cam and said second cam limiting the degree of said advancement; a third cam revolubly carried by said drive member adjacent said drive cam and having a major radius surface and a minor radius surface and further having a short radial surface extending outward from the minor radius surface sufiicient to form an abutment for said cam follower, and a nonradial surface continuing from said short radial surface rearwardly to said major radius surface; spring means for advancing said third cam to have its said short radial surface ahead of said radial surface of said drive cam; and abutment means between said drive cam and said third cam limiting the degree of advancement of the third cam.

3. A cam and cam follower structure comprising a driving member; a drive cam fixed to said member, said cam having a major radius surface and a minor radius surface and a non-radial surface therebetween sloping rearwardly in respect to direction of rotation of the cam; a second cam revolubly carried by said member adjacent said drive cam, having a major radius surface and a minor radius surface and a substantially radially disposed surface therebetween; spring means normally advancing in direction of the drive cam rotation said radially disposed surface ahead of said drive cam non-radial surface; abutment means between the drive cam and said second cam limit ing the degree of said advancement; a third cam revolubly carried by said drive member adjacent said drive cam and having a major radius surface and a minor radius surface and further having a short radial surface extending outward from the minor radius surface sufficient to form an abutment for said cam follower, and a non-radial surface continuing from said short radial surface rearwardly to said major radius surface; spring means for advancing said third cam to have its said short radial surface ahead of said radial surface of said drive cam; and abutment means between said drive cam and said third cam limiting the degree of advancement of the third cam; to position said short radial surface intermediate the positions of said drive cam non-radial surface and of said second cam radial surface.

JOSEPH H. STALEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 521,257 Brown June 12, 1894 1,290,201 Homans Jan. 7, 1919 1,831,605 Porter Nov. 10, 1931 2,086,090 Streckfuss Sept. 29, 1942 2,297,090 Weaver Sept. 29, 1942 

